azvrod

Hi guys, Im turning to the brain trust on this one. Here is the issue: Under prolonged boost my car pops the dipstick (it is loose but I zip tie it down), and it is blowing a considerable amount of oil mist out of the breather cap. This created an issue when I was running an under hood SC air filter and it was also sucking in that same considerable amount of oil. Here are the facts:

1) Catch can does not seem to be catching any oil anymore
2) Car does not blow any smoke
3) Car seems to be making as much power as ever
4) ECS 1500 making 12lbs of boost on stock 243 heads and bottom end
5) Slightly detuned speed density tune, making about 550 at the wheels
6) Checked the PCV valve running from the catch can and seems to be flowing from the intake valley, but not back from the TB..which is good?
7) Did a compression check and all cylinders were about 155, with a high of 165, a low of 150
8) Started a leak down test, but had a bad gauge, so aborted the second time around, but the one cylinder I did check with the good gauge was about 35% leakage (motor was cold and it was abou 60 degrees out, and assuming I had TDC)
9) Car idles fine
10) No puffing out of the dipstick
11) Went through about a quart of oil in a hard track day..most of which I think ended up on the motor via the breather cap

So in short, I dont think I have a broken piston and or bad rings..I thinks its a pressure evac problem.. and or Im just over preasurizing the stock motor.

Now all that being said, Im going to be going back to NA (for road racing), so does it really matter (i.e. might I really have a cracked piston)?

Sorry for the diatribe, but thank you for your time and opinions!

KJ

azvrod

Please move to the C5 FI Forum..my bad..sorry!

Unreal

Get a nice MM can setup, and enjoy.

ZincGT

post a pic of your setup

azvrod

Thanks Unreal, but pardon my ignorance; What is a MM setup?

azvrod

Thanks ZincGt here are some pics. I pulled the catch can up so you could see the setup, second pic shows the oil cap breather better.

azvrod

Thanks Unreal, I think I figured it oul, MM= Mighty Mouse?

Unreal

Yes.

You don't have a catchcan, you have a $15 air compressor oil seperator. A blown vette needs more than that, or you will damage seals and have issues as you are.

ZincGT

azvrod

Thank you so much guys, I sent a note to MM and he already got back with me and will be helping with a propoer set up.

TurboLX

A properly installed cyclonic separator like the Mann&Hummel ProVent on a closed system (no breather on the cap!) will outperform ANY other catch can system. Period. I use them on every boosted build I do. LPE sells them, but they are also available from several other sources. You will have to follow their specification for and make your own hose connections, but it's worth it.

Unreal

I potentially disagree with that. It all depends on what you mean by outperform? Separate oil better? Control crank case pressure better? Prevent seals blowing out?

If you are talking about preventing oil from entering, then I can get that. if you are talking about controlling crank case pressure, I disagree.

schpenxel

I bought one of those originally but couldn't find a decent way to mount it with the supercharger installed. It was pretty big if it's the same one I'm thinking of. Not to say there isn't a way, but didn't seem to be a simple one

You can find them on sites other than LPE's for a fraction of what they charge (I'm sure everyone is shocked by that)

Kingtal0n

the separator was on the intake manifold suction. So the check valve (PCV valve) is shut during boost -> There is no flow in that line during boost.

The filter on the cover provided crankcase pressure relief during WOT. Thats exactly the same thing that the MM catch can does: it has a relief for pressure on top.

So adding one isn't going to change anything about the way pressure is relieved from the engine during WOT.

Unreal

You should call David and find out more about his cans. That filter on top does not do the exact same thing as his setup.

Kingtal0n

pretty freaking obvious there is a huge filter on top of the can letting out crankcase pressure.

https://www.corvetteforum.com/forums...2980047544.jpg


I discussed this with him at length on LS1tech because this is not a complete PCV system. His response was something like, and I am paraphrasing, "this simplifies and eliminates a portion of the pcv system, because most owners remove their high quality paper filter systems and change their oil often enough to make any difference negligible"

to which I had to agree, it probably will not adversely affect engine life on the oil system side, not having a fresh air restrictor/pcv system intact. However I still recommend owners keep their high quality paper filtration system on the vehicle. You know, OEM elements for filters. If you turn the power up and make too much for it, then you customize a box to hold two or three of them, or another kind of paper filter. I put a diesel paper cone 4" on the last one. Some are washable, reusable.

Unreal

What isn't obvious is the one way valve below that, that only allows pressure out, unlike just a filter on a valve cover. So no, it does not work exactly the same as a filter on a valve cover. On the MM cans it is a safety device for an over pressure situation, not just an open filter all the time.

realcanuk

I have never seen an issue with David's (MM) systems as long as it's installed properly. Constantly see issues discussed running other systems. After trying another leading brand I realize that his stuff just works. I wouldn't even consider any other myself.

azvrod

Hi guys, I seem to have started a kerffulfle re proper catch can setup, but I wanted to post my compression and leak down results (I was trying to eliminate a cracked piston as the source of my blow by issue). Now, my disclaimer is that I dont have a lot of faith in the $30.00 harbor freight leak down tester I bought.


#1= 165 psi, 30% leak
#3= 155 psi, 30% leak
#5= 150 psi, 35% leak
#7= 155 psi, 25% leak

#2= 155 psi, 25% leak
#4= 155 psi, 30% leak
#6= 160 psi, 30% leak
#8= 155 psi, 35% leak

So I think they are well within each other, but arent the compresson and leak down tests indicating that the enigine is uniformly having too much blow by? Is this a result of running too much boost on a stock bottom end? So in other words, no one cylinder is the issue, its all the cylinders combined?

Other notes: The car does not blow smoke and seems to be making plenty of power.

Thanks for your feedback and input!!

KJ

azvrod

Oh I forgot to say, we used a scope to make sure the pistons were TDC